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Registros recuperados: 8
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Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea ArchiMer
Lamy, D.; Jeanthon, C.; Cottrell, M. T.; Kirchman, D. L.; Van Wambeke, France; Ras, J.; Dahan, O.; Pujo-pay, M.; Oriol, L.; Bariat, L.; Catala, P.; Cornet-barthaux, V.; Lebaron, P..
Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24398/22417.pdf
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Flow cytometric assessment of specific leucine incorporation in the open Mediterranean ArchiMer
Talarmin, A.; Van Wambeke, France; Catala, P.; Courties, C.; Lebaron, P..
The surface of the Mediterranean Sea is a low-phosphate-low-chlorophyll marine area where marine heterotrophic prokaryotes significantly contribute to the biogeochemical cycles of all biogenic elements such as carbon, notably through the mineralization of dissolved organic compounds. Cell-specific leucine incorporation rates were determined in early summer in the open stratified Mediterranean Sea. The bulk leucine incorporation rate was on average 5 +/- 4 pmol leu l(-1) h(-1) (n = 30). Cell-specific 3H-leucine incorporation rates were assayed using flow cytometry coupled to cell sorting. Heterotrophic prokaryotes (Hprok) were divided into cytometric groups according to their side scatter and green fluorescence properties: high nucleic acid containing cells...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24394/22407.pdf
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Introduction to the Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean (BOUM) experiment ArchiMer
Moutin, T.; Van Wambeke, France; Prieur, L..
The overall goal of the BOUM (Biogeochemistry from the Oligotrophic to the Ultraoligotrophic Mediterranean) experiment was to obtain a better representation of the interactions between planktonic organisms and the cycle of biogenic elements in the Mediterranean Sea (MS), in the context of global climate change and, more particularly, on the role of the ocean in carbon sequestration through biological processes. The BOUM experiment was organized around three main objectives: (1) to give a longitudinal description of the biogeochemistry and the biological diversity of the MS during the strongest stratified period, (2) to study processes at the centre of three anticyclonic eddies, and (3) to obtain a representation of the main biogeochemical fluxes and the...
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Ano: 2012 URL: http://archimer.ifremer.fr/doc/00133/24384/22400.pdf
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Lack of P-limitation of phytoplankton and heterotrophic prokaryotes in surface waters of three anticyclonic eddies in the stratified Mediterranean Sea ArchiMer
Tanaka, T.; Thingstad, T. F.; Christaki, U.; Colombet, J.; Cornet-barthaux, V.; Courties, C.; Grattepanche, J. -d.; Lagaria, A.; Nedoma, J.; Oriol, L.; Psarra, S.; Pujo-pay, M.; Van Wambeke, France.
We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediterranean Sea using nutrient manipulated microcosms during summer 2008. Experiments were carried out with surface waters at the center of anticyclonic eddies in the Western Basin, the Ionian Basin, and the Levantine Basin. In situ, the ratio of N to P was always higher in both dissolved and particulate organic fractions compared to the Redfield ratio, suggesting a relative P-starvation. In each experiment, four different treatments in triplicates (addition of ammonium, phosphate, a combination of both, and the unamended control) were employed and chemical and biological parameters monitored throughout a 3-4 day incubation. Temporal changes of turnover time of...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24395/22406.pdf
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Microbial food webs and metabolic state across oligotrophic waters of the Mediterranean Sea during summer ArchiMer
Christaki, U.; Van Wambeke, France; Lefevre, D.; Lagaria, A.; Prieur, L.; Pujo-pay, M.; Grattepanche, J. -d.; Colombet, J.; Psarra, S.; Dolan, J. R.; Sime-ngando, T.; Conan, Pascal; Weinbauer, M. G.; Moutin, T..
The abundance and activity of the major members of the heterotrophic microbial community - from viruses to ciliates - were studied along a longitudinal transect across the Mediterranean Sea in the summer of 2008. The Mediterranean Sea is characterized by a west to east gradient of deepening of DCM (deep chlorophyll maximum) and increasing oligotrophy reflected in gradients of biomass and production. However, within this well documented longitudinal trend, hydrological mesoscale features exist and likely influence microbial dynamics. Here we present data from a W-E transect of 17 stations during the period of summer stratification. Along the transect the production and fate of organic matter was investigated at three selected sites each one located in the...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24400/22422.pdf
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Organic carbon dynamics in the Mediterranean Sea: An integrated study ArchiMer
Santinelli, Chiara; Sempere, Richard; Van Wambeke, France; Charriere, Bruno; Seritti, Alfredo.
Total (TOC) and dissolved (DOC) organic carbon vertical profiles were analyzed from 11 stations located in various regions of the Mediterranean Sea, together with the distribution of other physical, chemical and biological parameters. TOC showed the highest concentrations (68-83 mu M) above the pycnocline, followed by a marked decrease to values of 45-48 mu M at 100-200 m. Below 200 m, values of 40-45 mu M were observed. The excess TOC and DOC occurring at each station was calculated by subtracting 48 mu M from the observed concentrations. The stock of the excess TOC and DOC increased eastward; while surface DOC mineralization rates decreased from 1.5 mu M d(-1) to 0.26 mu M d(-1) eastward. The integrated average of the biological parameters in the...
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Ano: 2012 URL: https://archimer.ifremer.fr/doc/00601/71278/69686.pdf
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The effects of nutrient additions on particulate and dissolved primary production and metabolic state in surface waters of three Mediterranean eddies ArchiMer
Lagaria, A.; Psarra, S.; Lefevre, D.; Van Wambeke, France; Courties, C.; Pujo-pay, M.; Oriol, L.; Tanaka, T.; Christaki, U..
We examined the effects of nutrient additions on rates of (14)C-based particulate and dissolved primary production as well as O(2)-based metabolic rates in surface waters (8 m) of three anticyclonic eddies, located in the Western, Central and Eastern Mediterranean. Ship-board microcosm experiments employing additions of inorganic nitrogen (+N) and phosphorus (+P), alone and in combination (+NP), were conducted in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone (+P). Percent extracellular release of...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24401/22418.pdf
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Vertical and longitudinal gradients in HNA-LNA cell abundances and cytometric characteristics in the Mediterranean Sea ArchiMer
Van Wambeke, France; Catala, P.; Pujo-pay, M.; Lebaron, P..
Heterotrophic bacterioplankton abundance and production were investigated with depth (down to bathypelagic layers) and with longitude (from 4.9 degrees E to 32.7 degrees E) along a cruise track across the Mediterranean Sea in early summer 2008. Abundances and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were determined using flow cytometry. Contrary to what is generally observed, the relative importance of HNA cells, as a percent of total cells, (%HNA, range 30-69%) was inversely related to bacterial production (range 0.15-44 ngC l(-1) h(-1)) although the negative relation was weak (log-log regression r(2) = 0.19). The %HNA as well as the mean side...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00133/24390/22404.pdf
Registros recuperados: 8
Primeira ... 1 ... Última
 

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